1. Field of the Invention
The present invention relates to an engine intake structure for a small boat, and particularly to an engine intake structure for a small boat having intake pipes extending sideways from cylinders provided in the engine, and these intake pipes being housed inside an intake box.
2. Description of Background Art
As a small boat for gliding over the surface of the sea or a lake, there is a known a small propelled boat driven having a water jet propulsion unit attached to the rear of the boat body. The boat is driven by taking in water from the bottom of the boat using the water jet propulsion unit and spraying the taken in water to the rear. This small boat is provided with an engine intake structure for taking in external air into an intake box, and introducing the taken in external air to intake pipes, as a structure for introducing air into a cylinder. See for example, Japanese patent Laid-open No. 2003-2292.
FIG. 13 is a reproduction of FIG. 7(a) of patent Japanese patent Laid-open No. 2003-2292. However, the reference numerals have been changed. The engine intake structure 200 of the small boat has four intake passages 202 . . . (only one is shown in the drawing) extending above a four cylinder engine 201, respective porous members 204 (in the following called “mesh members”) attached to intake opening 203 . . . of these intake passages 202 . . . , with the respective intake openings 202 . . . being arranged inside an intake box 205, and this intake box 205 is attached to an upper part of the engine 201 with an air cleaner element 206 being housed inside the intake box 205 and the intake box 205 being covered by a cover 207.
With the engine intake structure 200 for the small boat, air is introduced from an external air introduction opening 208 of the intake box 205, and the introduced air passes through the air cleaner element 206 and is introduced to the inside of the intake box. The introduced air is introduced to the intake opening 203 . . . through the mesh members 204 . . . , and introduced into the intake pipes 202 . . . from the intake openings 203 . . . .
The air cleaner element 206 is housed inside the intake box 205, and external air passes through the air cleaner element 206 and is introduced into the intake box 205. In this way, dust particles etc. in the air are removed by the air cleaner element 206, and that air is introduced into the intake box. Also, mesh members 204 . . . are attached to the intake openings 203 . . . of the intake pipes 202 . . . , to form a flame arrester.
Here, in the engine intake structure 200 for a small boat, the air cleaner element adopts a cylindrical shape, but the air cleaner element 206 is comparatively large. As the air cleaner element 206 is housed inside the intake box 205, the intake box becomes large. As this large intake box 205 is incorporated into the boat body of a small boat, it is necessary to ensure a comparatively large space inside the boat body.
However, since the engine 201 and various components are arranged inside the boat body of the small boat, it is difficult to ensure a comparatively large space inside the boat body. Therefore, in order to ensure space for attachment of the large intake box 205, studies to determine layout (arrangement) of various components take time, and this hinders increase in productivity.